Shear strength developments during shock loading in tantalum alloys: Effects of cold work and alloying

The development of shear strength behind the shock front in tantalum alloys of 2.5 and 10wt% tungsten has been monitored by the use of laterally mounted stress gauges. Results show that in common with pure tantalum, shear strength decreases behind the shock front. At 2.5wt%, we believe that tungsten modifies the mechanical response by mitigating the effects of interstitial solute atoms, thus easing dislocation motion, as evidenced by the smaller reduction in shear strength compared to pure tantalum. At higher tungsten levels, it would appear that this is overcome by an overall increase in Peierls stress, which renders dislocation motion more difficult, thus giving the alloy a response more in common with that of the pure metal. Cold rolling of the 2.5% W alloy also appears to increase shear strength reduction behind the shock front (compared to the annealed alloy), although at present the reasons for this are unclear.